By: Felid (Felid.delete@this.mailinator.com), November 16, 2012 12:46 pm
Room: Moderated Discussions
Eric Bron (eric.bron.delete@this.zvisuel.privatefortest.com) on November 16, 2012 9:47 am wrote:
> > I think it was only 128-bit in the first place (I mean the internal datapath here).
>
> My understanding is that VEX.256 packed divides and square roots are processed as 2 x 128-bit operations
> on Sandy Bridge (there is a single division unit in a single 128-bit stack, unlike FP ADD/FP MUL) but as
> a single operation on Ivy Bridge (there is 2 division units in two 128-bit stacks, like FP ADD/FP MUL)
Wrong. Divider-rooter is the only large 128-bit unit left in vector datapath. This one is just «kind of» pipelined. SP, DP & EP are now divided in 7, 14 & 18 clks (SB had — 14, 22 & 24).
> > I think it was only 128-bit in the first place (I mean the internal datapath here).
>
> My understanding is that VEX.256 packed divides and square roots are processed as 2 x 128-bit operations
> on Sandy Bridge (there is a single division unit in a single 128-bit stack, unlike FP ADD/FP MUL) but as
> a single operation on Ivy Bridge (there is 2 division units in two 128-bit stacks, like FP ADD/FP MUL)
Wrong. Divider-rooter is the only large 128-bit unit left in vector datapath. This one is just «kind of» pipelined. SP, DP & EP are now divided in 7, 14 & 18 clks (SB had — 14, 22 & 24).
